1 files changed, 28 insertions, 27 deletions

diff --git a/lib/std/formatfloat.nim b/lib/std/formatfloat.nim
index 6f2383760..9258245f6 100644
--- a/lib/std/formatfloat.nim
+++ b/lib/std/formatfloat.nim
@@ -7,10 +7,10 @@
 #    distribution, for details about the copyright.
 #
 
+## This module implements formatting floats as strings.
+
 when defined(nimPreviewSlimSystem):
   import std/assertions
-else:
-  {.deprecated: "formatfloat is about to move out of system; use `-d:nimPreviewSlimSystem` and import `std/formatfloat`".}
 
 proc c_memcpy(a, b: pointer, size: csize_t): pointer {.importc: "memcpy", header: "<string.h>", discardable.}
 
@@ -28,15 +28,15 @@ proc writeFloatToBufferRoundtrip*(buf: var array[65, char]; value: BiggestFloat)
   ##
   ## returns the amount of bytes written to `buf` not counting the
   ## terminating '\0' character.
-  result = toChars(buf, value, forceTrailingDotZero=true)
+  result = toChars(buf, value, forceTrailingDotZero=true).int
   buf[result] = '\0'
 
 proc writeFloatToBufferRoundtrip*(buf: var array[65, char]; value: float32): int =
-  result = float32ToChars(buf, value, forceTrailingDotZero=true)
+  result = float32ToChars(buf, value, forceTrailingDotZero=true).int
   buf[result] = '\0'
 
-proc c_sprintf(buf, frmt: cstring): cint {.header: "<stdio.h>",
-                                    importc: "sprintf", varargs, noSideEffect.}
+proc c_snprintf(buf: cstring, n: csize_t, frmt: cstring): cint {.header: "<stdio.h>",
+                                    importc: "snprintf", varargs, noSideEffect.}
 
 proc writeToBuffer(buf: var array[65, char]; value: cstring) =
   var i = 0
@@ -49,7 +49,7 @@ proc writeFloatToBufferSprintf*(buf: var array[65, char]; value: BiggestFloat):
   ##
   ## returns the amount of bytes written to `buf` not counting the
   ## terminating '\0' character.
-  var n: int = c_sprintf(addr buf, "%.16g", value)
+  var n = c_snprintf(cast[cstring](addr buf), 65, "%.16g", value).int
   var hasDot = false
   for i in 0..n-1:
     if buf[i] == ',':
@@ -86,36 +86,37 @@ proc writeFloatToBuffer*(buf: var array[65, char]; value: BiggestFloat | float32
 
 proc addFloatRoundtrip*(result: var string; x: float | float32) =
   when nimvm:
-    doAssert false
+    raiseAssert "unreachable"
   else:
     var buffer {.noinit.}: array[65, char]
     let n = writeFloatToBufferRoundtrip(buffer, x)
-    result.addCstringN(cstring(buffer[0].addr), n)
+    result.addCstringN(cast[cstring](buffer[0].addr), n)
 
 proc addFloatSprintf*(result: var string; x: float) =
   when nimvm:
-    doAssert false
+    raiseAssert "unreachable"
   else:
     var buffer {.noinit.}: array[65, char]
     let n = writeFloatToBufferSprintf(buffer, x)
-    result.addCstringN(cstring(buffer[0].addr), n)
-
-proc nimFloatToString(a: float): cstring =
-  ## ensures the result doesn't print like an integer, i.e. return 2.0, not 2
-  # print `-0.0` properly
-  asm """
-    function nimOnlyDigitsOrMinus(n) {
-      return n.toString().match(/^-?\d+$/);
-    }
-    if (Number.isSafeInteger(`a`))
-      `result` = `a` === 0 && 1 / `a` < 0 ? "-0.0" : `a`+".0"
-    else {
-      `result` = `a`+""
-      if(nimOnlyDigitsOrMinus(`result`)){
-        `result` = `a`+".0"
+    result.addCstringN(cast[cstring](buffer[0].addr), n)
+
+when defined(js):
+  proc nimFloatToString(a: float): cstring =
+    ## ensures the result doesn't print like an integer, i.e. return 2.0, not 2
+    # print `-0.0` properly
+    {.emit: """
+      function nimOnlyDigitsOrMinus(n) {
+        return n.toString().match(/^-?\d+$/);
+      }
+      if (Number.isSafeInteger(`a`))
+        `result` = `a` === 0 && 1 / `a` < 0 ? "-0.0" : `a`+".0";
+      else {
+        `result` = `a`+"";
+        if(nimOnlyDigitsOrMinus(`result`)){
+          `result` = `a`+".0";
+        }
       }
-    }
-  """
+    """.}
 
 proc addFloat*(result: var string; x: float | float32) {.inline.} =
   ## Converts float to its string representation and appends it to `result`.